Short-term control of cardiovascular function: estimation of control parameters in healthy humans

1996 ◽  
Vol 270 (2) ◽  
pp. H651-H660 ◽  
Author(s):  
K. Toska ◽  
M. Eriksen ◽  
L. Walloe
Keyword(s):  
Mathematical Model ◽  
Arterial Pressure ◽  
Closed Loop ◽  
Cardiovascular Responses ◽  
Pressure Control ◽  
Open Loop ◽  
Control Parameters ◽  
Short Term ◽  
Model Simulations ◽  
Healthy Humans

In a previous study, we recorded short-term cardiovascular responses after a steep increase in arterial pressure in healthy humans [Am. J. Physiol. 266 (Heart Circ. Physiol. 35): H199-H211, 1994]. The aim of the present study was to develop a mathematical model of the baroreflex control of arterial pressure, to use this model with the previously recorded data to estimate unknown parameters in the reflex control loop, and then to analyze the overall open- and closed-loop performance of the system by model simulations with use of individual sets of optimal parameters. The mathematical model consists of a heart, a linear elastic arterial reservoir, and two parallel resistive vascular beds. The arterial baroreflex loop is modeled by two separate time domain processing objects, each with its own gain, time constant, and delay, to simulate the action of a sympathetic signal to the peripheral vascular bed and a parasympathetic signal to the heart. In repeated model simulations, the control parameters in the model were systematically adjusted by an automated algorithm that minimized the deviations between the time courses of the cardiovascular variables simulated by the model and the previously recorded responses in each individual. In all 10 subjects, the short-term cardiovascular responses were adequately simulated by using individual sets of parameters in the model. Open-loop transfer functions for arterial pressure control were obtained by using the individual sets of optimal model parameters in new simulation runs. Open-loop gain for arterial pressure control at nearly zero frequency (steady state) was between 0.9 and 4. Model simulations also indicated an underdampened response at 0.05-0.07 Hz in the closed-loop situation in four subjects, corresponding to peaks in the mean arterial pressor power spectra obtained from separate recordings of spontaneous variations in the resting situation.

scholarly journals DYNAMIC SIMULATION AND COMPOSITION CONTROL IN A 10 L MIXING TANK

REAKTOR ◽  
2012 ◽  
Vol 14 (2) ◽  
pp. 95
Author(s):  
Yulius Deddy Hermawan ◽  
Gogot Haryono
Keyword(s):  
Mathematical Model ◽  
Dynamic Simulation ◽  
Closed Loop ◽  
Step Function ◽  
Open Loop ◽  
Liquid Volume ◽  
Control Parameters ◽  
Software Environment ◽  
Composition Control ◽  
Volumetric Rate

The open loop experiment of composition dynamic in a 10 L mixing tank has been successfully done inlaboratory. A 10 L tank was designed for mixing of water (as a stream-1) and salt solution (as astream-2 with salt concentration, c2 constant). An electric stirrer was employed to obtain uniformcomposition in tank. In order to keep the liquid volume constant, the system was designed overflow. Inthis work, 2 composition control configurations have been proposed; they are Alternative-1 andAlternative-2. For Alternative-1, the volumetric-rate of stream-1 was chosen as a manipulatedvariable, while the volumetric-rate of stream-2 was chosen as a manipulated variable for Alternative-2. The composition control parameters for both alternatives have been tuned experimentally. Thevolumetric-rate of manipulated variable was changed based on step function. The outlet stream’scomposition response (c3) to a change in the input volumetric-rate has been investigated. Thisexperiment gave Proportional Integral Derivative (PID) control parameters. The gain controllers Kc[cm6/(gr.sec)] for Alternative-1 and Alternative-2 are -34200 and 40459 respectively. Integral timeconstant ( tI) and Derivative time constant (tD) for both alternatives are the same, i.e. tI = 16 second,and tD = 4 second. Furthermore, closed loop dynamic simulation using computer programming wasalso done to evaluate the resulted tuning parameters. The developed mathematical model ofcomposition control system in a mixing tank was solved numerically. Such mathematical model wasrigorously examined in Scilab software environment. The results showed that closed loop responses inPID control were faster than those in P and PI controls.

Peripheral vasoconstriction shortly after onset of moderate exercise in humans

1994 ◽  
Vol 77 (3) ◽  
pp. 1519-1525 ◽  
Author(s):  
K. Toska ◽  
M. Eriksen
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Cardiovascular Responses ◽  
Pressure Control ◽  
Set Point ◽  
Peripheral Vasoconstriction ◽  
Cholinergic Blockade ◽  
Healthy Humans ◽  
Exercise Period

The immediate cardiovascular responses at the onset of supine dynamic leg exercise were studied by noninvasive methods in healthy humans. Total peripheral conductance (TPC), heart rate, and cardiac output increased very rapidly at the onset of exercise. Mean arterial pressure (MAP) showed a moderate anticipatory increase during a 10-s countdown to exercise and then decreased (but not below resting level) during the first 10 s of exercise. The TPC response was biphasic, and TPC started to fall from its peak value approximately 12 s after onset of exercise. This peripheral vasoconstriction increased MAP. After 25 s, the cardiovascular variables were stable for the rest of the 2-min exercise period. In the same subjects, cholinergic blockade was induced by atropine sulfate (0.035 mg/kg) and resting cardiac output, MAP, and TPC increased considerably. The exercise protocol was repeated after atropine, and the increase in heart rate at onset of exercise was slower and smaller. MAP decreased and remained depressed throughout the exercise period. A monophasic increase in TPC was seen. We suggest that, in the normal situation, the biphasic response in TPC reflects a baroreflex sympathetic vasoconstriction very shortly after onset of exercise and that this response is due to a rapid increase in set point for arterial pressure control at the onset of exercise. After cholinergic blockade, MAP was probably continuously well above the set point for arterial pressure control both before and during exercise and no reflex vasoconstriction was observed in this situation.

Short-Term Response of a Bridge-Winglet Sectional Model under Active Flutter Control

2020 ◽  
Vol 20 (08) ◽  
pp. 2050084
Author(s):  
Bowen Yan ◽  
Ke Li ◽  
Shaopeng Li ◽  
Guowei Qian ◽  
Yi Hui
Keyword(s):  
Closed Loop ◽  
Aerodynamic Force ◽  
Open Loop ◽  
Closed Loop Control ◽  
Control Effect ◽  
Short Term ◽  
Loop Control ◽  
Control Interval ◽  
Sectional Model ◽  
Term Response

Active winglets, with a manually controlled attitude angle, can take advantage of the self-excited force to suppress the flutter tendency of a bridge girder. Previous studies mostly focused on the effectiveness and robustness under long-term closed-loop control. However, the deck-winglet system’s short-term response, due to the memory effect of the aerodynamic force, is of concern. A bridge sectional model with active winglets was developed to investigate this problem. Experiments with different phase shifts between the members of the winglet pair were carried out in a wind tunnel. We found that the influence residue of an instantaneous change of the control pattern lasted about three pitching cycles, indicating that a large control interval was acceptable for practical applications. A theoretical relationship between the control effect and control phase was derived to explain the results of the open-loop control. The system responses under different control intervals were analyzed by the closed-loop control, demonstrating that a large control interval was acceptable if some time-consuming algorithms are used in a practical bridge’s flutter control operation.

Lack of time-dependent augmentation of carotid sinus baroreflex system after vagotomy

1982 ◽  
Vol 242 (4) ◽  
pp. H580-H584
Author(s):  
H. Hosomi ◽  
K. Yokoyama
Keyword(s):  
Control System ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Pressure Control ◽  
Open Loop ◽  
Carotid Sinus Baroreflex ◽  
Stepwise Reduction ◽  
Intact Condition ◽  
Pressure Control System ◽  
Arterial Pressure Control System

The purpose of this experiment was to study whether the carotid sinus baroreflex system (CS system) increases its gain with time after vagotomy in compensation for the loss of the vagally mediated arterial pressure control system (V system). In 7 dogs anesthetized with pentobarbital sodium we determined the responsiveness of the V system by repeatedly measuring the overall open-loop gain (G) of the negative feedback control system. G was assessed as (delta API/delta APS) -- 1, where delta API and delta APS are, respectively, the immediate and steady-state falls in arterial pressure at the aortic arch following a stepwise reduction in blood volume. delta API, delta APS, and G in intact condition were -12.0 +/- 1.8 mmHg, -1.1 +/- 0.2 mmHg, and 10.1 +/- 0.7 (SD), respectively. delta API, delta APS, and G after vagotomy, i.e., G of the CS system (GCS), were -15.6 +/- 3.6 mmHg, -6.4 +/- 1.9 mmHg, and 1.6 +/- 0.4 GCS did not change with time over 4 h after vagotomy. We conclude that the CS system cannot augment its ability to restore arterial pressure in compensation for the lost function of the V system within 4 h after vagotomy in the anesthetized dog.

scholarly journals Servo-Controlled Hind-Limb Electrical Stimulation for Short-Term Arterial Pressure Control

2009 ◽  
Vol 73 (5) ◽  
pp. 851-859 ◽  
Author(s):  
Toru Kawada ◽  
Shuji Shimizu ◽  
Hiromi Yamamoto ◽  
Toshiaki Shishido ◽  
Atsunori Kamiya ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Hind Limb ◽  
Pressure Control ◽  
Short Term

Modelling and Control of HSFDs for Active Control of Rotor-Bearing Systems

1994 ◽  
Author(s):  
A. El-Shafel ◽  
J. P. Hathout
Keyword(s):  
Active Control ◽  
Closed Loop ◽  
Transient Behavior ◽  
Pressure Control ◽  
Fast Response ◽  
Open Loop ◽  
Loop System ◽  
Squeeze Film ◽  
Open Loop System ◽  
Loop Control

This paper summarizes the development of hybrid squeeze film dampen (HSFDs) for active control of rotor vibrations. Previously, it was shown both theoretically and experimentally that HSFDs can be used for controlling rotor vibrations (El-Shafei, 1993). This is done by controlling the flow in a squeeze film damper through movable end seals, thus achieving the ability to change the damper from a short damper to a long damper and vice versa. However, the control of the HSFD was manual. In this paper, an automatically controlled circuit is developed for the HSFD, incorporating a pressure control servovalve for controlling the pressure in the scaling chambers. A complete mathematical model of this open-loop system is developed and is implemented on a digital computer. The transient behavior of the system, including the sealing ring dynamics, illustrates that the open-loop system exhibits well behaved, stable, and fast response. In addition it is shown that the HSFD can achieve any amount of damping between the short and long damper modes through the accurate positioning of the sealing rings. The simulation results illustrate that the automatically controlled HSFD can be a very useful device for the active control of rotors. A closed loop control strategy with feedback on rotor speed is also investigated both from the points of view of steady state and transient behaviors. It is shown that this closed loop strategy results in a much improved behavior of the rotor system.

Estimation of open-loop gain of canine arterial pressure control system by a new method

1981 ◽  
Vol 240 (6) ◽  
pp. H832-H836 ◽  
Author(s):  
H. Hosomi ◽  
K. Yokoyama
Keyword(s):  
Control System ◽  
Arterial Pressure ◽  
Pressure Change ◽  
Pressure Control ◽  
Systemic Arterial Pressure ◽  
Open Loop ◽  
Loop Gain ◽  
Reflex Gain ◽  
Pressure Control System ◽  
Arterial Pressure Control System

We developed a method to estimate an overall open-loop gain of the arterial pressure control system without surgically opening the reflex loop. Dogs anesthetized by intravenous injection of Nembutal (35 mg/kg body wt) were bled by 2 ml/kg body wt within 2-3 s through a catheter inserted into the abdominal aorta. Arterial pressure change after the quick hemorrhage was monitored via a catheter placed in the aortic arch for more than 2 min. The overall open-loop gain of the lumped arterial pressure control system was assessed as (delta API/delta APs)-1, where delta API is the immediate fall and delta APs the steady-state fall in mean arterial pressure obtained by a filter with a 2-s time constant. The advantage of this method is that the overall open-loop gain can be estimated under the closed-loop condition in which the baroreceptor reflexes operate naturally around the existing range of systemic arterial pressure. This enables one to study time-varying characteristics of the reflex gain. The disadvantage is that the substantial constituents of the lumped reflex system remain to be confirmed.

Unstable state of the arterial pressure control system after a mild hemorrhage

1978 ◽  
Vol 235 (5) ◽  
pp. R279-R285
Author(s):  
H. Hosomi
Keyword(s):  
Heart Rate ◽  
Control System ◽  
Arterial Pressure ◽  
Rapid Test ◽  
Pressure Oscillation ◽  
Pressure Control ◽  
Open Loop ◽  
Unstable State ◽  
Pressure Control System ◽  
Arterial Pressure Control System

The stability of the arterial pressure control system after a mild hemorrhage (5 ml/kg body wt) was studied in 10 anesthetized cats by analyzing the responses of arterial pressure and of heart rate and the dead time (L) of heart rate response to a minute, rapid test hemorrhage (1 ml/kg body wt). The overall open-loop gain (H) of the arterial pressure control system was estimated from the ratio of arterial pressure fall immediately after the quick hemorrhage over the steady-state fall. Increases in H and L were correlated with the tendency of the arterial pressure control system to be unstable and oscillate. Oscillation in arterial pressure was always accompanied by a marked increase in heart rate (deltaHR), which represents an enhanced activity of the sympathetic nervous system and serves to restore arterial pressure toward the prehemorrhage level. The present study indicates that the magnitude of deltaHR also serves as a good predictor of arterial pressure oscillation.

Sign in / Sign up

Export Citation Format

Share Document